1. Field of the Invention
This invention relates generally to the formation of laminate circuit structures by photolithographic techniques, and more particularly to a method of forming composite laminate structures which utilizes a multiplicity of preformed circuits having signal and voltage planes and a laminate structure having a ground plane without signal planes.
2. Background Information
A conventional technique of forming a laminate circuit board structures includes forming layers of dielectric material and electrically conducting material to provide multiple layers of circuits and voltage planes. Voltage planes can be either ground plane or power plane, and are sometimes collectively referred to as power planes. In one prior art technique of forming such structure, layers of dielectric material and conducting material successively applied, i.e. the dielectric material is applied and then voltage planes are supplied thereon and if necessary through holes formed by the drilling or etching of through holes or blind vias. This technique relies on each successive step adding additional structure and the circuitry layers are formed individually; i.e., in each step in forming the signal planes the planes are formed after the formation of the prior layer of signal plane and forming the signal plane on formed power planes. This requires precession drilling to form the plated through holes all of which is time consuming, especially where there is a large number of drilled holes required to form plated through holes.
Thus it is desired to provide a relatively inexpensive photolithographic technique of forming a composite laminate structure from individual discrete laminate structures into a composite laminate structure.